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A LOW-COsT OPTIMIZATION APPROACH FOR sOLVING MINIMUM NORM LINEAR sYsTEMs AND LINEAR LEAsT-sQUAREs PROBLEMs

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Journal of Computational Mathematics 2024年第4期42卷 932-954页

作者： Debora Cores johanna Figueroa Defense University Center at the spanish Naval Academy Plaza de Espana36920 MarinPontevedraSpain Departamento de Matematica Facultad de MatematicaPontificia Universidad Catolica de ChileAv.Vicuna Mackenna 4860San JoaquinSantiago 894000Chile

Recently,the authors proposed a low-cost approach,named Optimization Approach for Linear systems(OPALs)for solving any kind of a consistent linear system regarding the structure,characteristics,and dimension of the coefficient matrix *** results obtained by this approach for matrices with no structure and with indefinite symmetric part were encouraging when compare with other recent and well-known *** this work,we proposed to extend the OPALs approach for solving the Linear Least-squares Problem(LLsP)and the Minimum Norm Linear system Problem(MNLsP)using any iterative low-cost gradient-type method,avoiding the construction of the matrices AT A or AAT,and taking full advantage of the structure and form of the gradient of the proposed nonlinear objective function in the gradient *** combination of those conditions together with the choice of the initial iterate allow us to produce a novel and efficient low-cost numerical scheme for solving both ***,the scheme presented in this work can also be used and extended for the weighted minimum norm linear systems and minimum norm linear least-squares *** include encouraging numerical results to illustrate the practical behavior of the proposed schemes.

关键词： Nonlinear convex optimization Gradient-type methods spectral gradient method Minimum norm solution linear systems Linear least-squares solution

Estimation of drag forces caused by natural woody vegetation of different scales

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Journal of Hydrodynamics 2014年第4期26卷 608-623页

作者： JALONEN johanna JRVEL Juha Department of Civil and Environmental Engineering Aalto University

To reliably estimate water levels and velocities in vegetated rivers and floodplains, flow resistance models based on physical plant properties are advantageous. The purpose of this study is （1） to assess the suitable parameterization of woody riparian vegetation in estimating the drag forces, （2） to address the effect of plant scale on the drag estimates and reconfiguration, and （3） to evaluate the applicability of three recently developed flow resistance models. Experiments on four tree species in a towing tank together with detailed characterization of tree properties were carried out to establish a novel dataset. Despite the variability in the tree height （0.9 m-3.4 m）, the stem, leaf and total areas proved to be suitable characteristic dimensions for estimating the flow resistance at different scales. Evaluations with independent data revealed that the tested models produced reasonable results. The performance of the models was controlled by the parameter values used rather than the model structure or the plant scale.

关键词： drag force flow resistance woody vegetation modelling

Cultivating more-than-human care: Exploring bird watching as a landscaping practice on the example of sand martins and flooded gravel pits

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Frontiers of Architectural Research 2022年第6期11卷 1205-1213页

作者： johanna Just Institute for Landscape and Urban studies Prof.Teresa Galí-IzardChair of Being AliveDepartment of ArchitectureETH ZürichCH-8093 ZürichSwitzerland

The environmental crisis has created a demand for practices that build awareness about the interconnections of diverse forms of life,allowing humans to understand complex earthly relationships and reconnect with the land they *** paper contributes to this debate by investigating bird watching activities and their relevance for architects and landscape *** upon multispecies studies and the notion of landscape thinking,it examines the potential of birding as a caring landscaping *** analyzes the relationship between birders and sand martins in two case studies and probes how birders develop attentiveness for the birds and their shared *** investigation suggests that birding fosters care beyond the observed *** can trigger a landscaping practice comparable to landscape thinking that helps humans reconnect with the land,fostering response-able spatial design practices.

关键词： More-than-human Care Birding Landscaping sand martin Gravel extraction

Finding stable multi-component materials by combining cluster expansion and crystal structure predictions

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npj Computational Materials 2023年第1期9卷 2137-2146页

作者： Adam Carlsson johanna Rosen Martin Dahlqvist Materials Design Department of PhysicsChemistryand Biology(IFM)Linköping UniversitySE-58183 LinköpingSweden

A desired prerequisite when performing a quantum mechanical calculation is to have an initial idea of the atomic positions within an approximate crystal *** atomic positions combined should result in a system located in,or close to,an energy ***,designing low-energy structures may be a challenging task when prior knowledge is scarce,specifically for large multi-component systems where the degrees of freedom are close to *** this paper,we propose a method for identification of low-energy crystal structures within multi-component systems by combining cluster expansion and crystal structure predictions with density-functional theory *** structure prediction searches are applied to the Mo_(2)AlB_(2) and sc2AlB_(2) ternary systems to identify candidate structures,which are subsequently used to explore the quaternary(pseudo-binary)(Mo_(x)sc_(1–x))2AlB_(2) system through the cluster expansion formalism utilizing the ground-state search ***,we show that utilizing low-energy structures found within the cluster expansion ground-state search as seed structures within crystal structure predictions of(Mo_(x)sc_(1–x))2AlB_(2) can significantly reduce the computational *** this combined approach,we not only correctly identified the recently discovered Mo_(4/3)sc_(2/3)AlB_(2) i-MAB phase,comprised of in-plane chemical ordering of Mo and sc and with Al in a Kagomélattice,but also predict additional low-energy structures at various *** result demonstrates that combining crystal structure prediction with cluster expansion provides a path for identifying low-energy crystal structures in multi-component systems by employing the strengths from both frameworks.

关键词： structure cluster crystal

The Role of Inertia and Dissipation in the Dynamics of the Director for a Nematic Liquid Crystal Coupled with an Electric Field

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Communications in Computational Physics 2015年第6期18卷 147-166页

作者： Peder Aursand johanna Ridder Department of Mathematical sciences Norwegian University of Science and TechnologyNO–7491 TrondheimNorway Department of Mathematics University of OsloP.O.Box NO-1053BlindernOslo-0316Norway

We consider the dynamics of the director in a nematic liquid crystal when under the influence of an applied electric *** an energy variational approach we derive a dynamic model for the director including both dissipative and inertial forces.A numerical scheme for the model is proposed by extending a scheme for a related variational wave *** experiments are performed studying the realignment of the director field when applying a voltage difference over the liquid crystal *** particular,we study how the relative strength of dissipative versus inertial forces influence the time scales of the transition between the initial configuration and the electrostatic equilibrium state.

关键词： Nematic liquid crystals Freedericksz transition dynamics of director fields

Experimental approaches to select tree species for forest restoration:effects of light,water availability and interspecific competition in degraded areas

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Journal of Forestry Research 2022年第4期33卷 1197-1207页

作者： johanna Croce Ernesto I.Badano Carolina B.Trigo Fernanda Martinez-Galvez Andrés Tálamo Laboratorio de Ecología Aplicada a la Conservación Instituto de Bio y Geociencias del Noroeste ArgentinoConsejo de Investigaciones Científi cas y Técnicas-Universidad Nacional de SaltaAvenida Bolivia 51504400 SaltaArgentina IPICYT/División de Ciencias Ambientales Instituto Potosino de Investigación Científi ca y TecnológicaCamino a la Presa San José2055Colonia Lomas 4^(a)Sección78216 San Luis PotosíMéxico

Knowing what native trees can recr uit on degraded areas allows selecting the best species to restore these ***,as this information is not often available,experimentation is required before large-scale *** study used ex situ experiments to make these decisions on *** with r-strategist plants,excessive solar radiation and water shortage commonly impair tree recruitment in open *** experiments focused on the interactions among these factors and were conducted with three pioneer species from seasonally dry forests of northwest Argentina,Anadenanthera colubrina,Ceiba chodatii and Jacaranda *** of each species were sown at two light levels(sunlight/shade),two rainfall levels(full/reduced)and two levels of interspecific competition(with/without competitor)in a tree *** emergence and survival were monitored over a year and the results indicate that species differentially respond to varying levels of light and *** of *** tolerated water shortages under elevated solar radiation,which are desirable features for forest *** of *** tolerated shade and drought,suggesting that they require shading for establishing in open ***,*** seedlings neither tolerated full sunlight nor water shortages,suggesting that this species requires shading and regular watering if used in *** of the effects of light and water,the survival of all species was reduced by interspecific *** results highlight the importance of experimentation for selecting the best species for forest restoration and can enhance the cost/benefit ratios of these actions.

关键词： Common-garden experiments Drought Ecological restoration Interspecific competition seedling survival shade

Nickela-electrocatalyzed sulfide and phosphine oxygenations with water

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science China Chemistry 2021年第6期64卷 873-874页

作者： Long Yang johanna Frey Lutz Ackermann Institut für Organische und Biomolekulare Chemie Georg-August-Universität GöttingenTammannstrasse 2Göttingen 37077Germany Wöhler Research Institute for sustainable Chemistry(WIsCh) Georg-August-Universität GöttingenTammannstrasse 2Göttingen 37077Germany

Molecular electrochemistry has emerged as an environmentally-friendly *** major recent momentum was gained in electrocatalyzed bond activations by earth-abundant 3 d transition metals[1],cost-effective nickela-electrocatalysis continuous to be underdevelopment for electrocatalysis[2].Nickel is an essential component of metalloproteins involved in catalytic aerobic oxygenation processes,for which nickel-dioxygen species were proposed as the key catalytic species[3].

关键词： catalyzed nickel Nickel

EULER sCHEME FOR FRACTIONAL DELAY sTOCHAsTIC DIFFERENTIAL EQUATIONs BY ROUGH PATHs TECHNIQUEs

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Acta Mathematica scientia 2019年第3期39卷 747-763页

作者： johanna GARZON samy TINDEL soledad TORREs Departamento de Matematicas Universidad Nacional de ColombiaBogota D.C.Colombia Department of Mathematics Purdue University150 N.University StreetW.LafayetteIN 47907USA Facultad de Ingenierza CIMF AV Universidad de ValparaisoCasilla 123-V4059 ValparaisoChile

In this note, we study a discrete time approximation for the solution of a class of delayed stochastic differential equations driven by a fractional Brownian motion with Hurst parameter H ∈(1/2,1). In order to prove convergence, we use rough paths techniques. Theoretical bounds are established and numerical simulations are displayed.

关键词： Fractional Brownian motion stochastic differential equations rough paths,discrete time approximation

What Do We Really Know about Cellulose Biosynthesis in Higher Plants?

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Journal of Integrative Plant Biology 2010年第2期52卷 161-175页

作者： Gea Guerriero johanna Fugelstad Vincent Bulone Division of Glycoscience School of BiotechnologyRoyal Institute of TechnologyAlbaNova University CenterSE-106 91 StockholmSweden

Cellulose biosynthesis is one of the most important biochemical processes in plant biology. Despite the considerable progress made during the last decade, numerous fundamental questions related to this key process in plant development are outstanding. Numerous models have been proposed through the years to explain the detailed molecular events of cellulose biosynthesis. Almost all models integrate solid experimental data with hypotheses on several of the steps involved in the process. speculative models are most useful to stimulate further research investigations and bring new exciting ideas to the field. However, it is important to keep their hypothetical nature in mind and be aware of the risk that some undemonstrated hypotheses may progressively become admitted. In this review, we discuss the different steps required for cellulose formation and crystallization, and highlight the most important specific aspects that are supported by solid experimental data.

关键词： cell What Do We Really Know about Cellulose Biosynthesis in Higher Plants